The sixth-grade teacher meant to show Sandy Springs Charter Middle School students an instructional video Tuesday from his personal laptop, WSB reported.

Instead, officials said, “a few seconds” of porn were displayed on the screen.

Fulton County Schools officials investigated the teacher, who eventually submitted a letter of resignation, WSB reported.

“It is our expectation that teachers and staff maintain a safe and appropriate instructional environment for all students,” a Fulton County Schools official said in a statement to the news station. “Our focus will continue to be student achievement and the safety or our students and staff.”